Soroche, acute mountain sickness (AMS), altitude sickness -- whatever you call it, it does not discriminate. The simple fact is, the higher you go above sea level, the thinner the oxygen in your blood becomes. By 10,000 feet oxygen levels have gone from roughly 98% saturation to 89%. This catches many travelers off-guard; young, old, man, woman, fit or not -- anyone is potentially at risk. The good news is that the majority of those who experience altitude sickness find it relatively mild and limiting -- NOT debilitating. And symptoms usually decline as altitude acclimatization occurs. All in all, don't be afraid, be smart. Coming prepared, and recognizing the signs are the best ways to combat altitude sickness.
Signs of altitude sickness include dizziness, headache, nausea/vomiting, trembling, clumsiness, poor sleep, lack of appetite or overall feeling of exhaustion or lethargy. Imagine a bad hangover -- not so fun. Many travelers coming off of a long flight tend to simply waive these symptoms off as jet-lag, maybe one too many bags of airplane peanuts or too much caffeine to counter the jet-lag.
It's hard to predict who will fall victim to altitude sickness, and who will not. A general rule of thumb: if you've experienced it before, you're likely to experience it again. It is much easier to prevent, than to treat, altitude sickness. Here are a few helpful tips to do just that.
Allow yourself time to acclimatize
Spend some sometime adjusting to your new environment - and take it easy the first few days at a higher altitude. This is the perfect excuse to site-see, take a leisurely stroll and check out a few local markets and cuisine. Eating a lot of carbohydrates, like breads, cereals, and pasta can also help prevent altitude sickness.
Drink lots of fluids, even if you're not thirsty. Because there is less oxygen in the atmosphere, you and your lungs will naturally work harder to get what you need. Combine that with exertion and sweating from trekking and you've potentially created the perfect recipe for dehydration. Start drinking water before you get on the plane and keep plenty on hand throughout your travels. It's a good idea to limit alcohol intake the first day or so at higher elevation as well.
If possible, ascending at a sensible rate (roughly a 1,000 feet gain in altitude per day) should give your body enough time to acclimatize as you ascend. But if you're hiking high passes, or flying into high altitude cities like Cusco, Peru or La Paz, Bolivia, a slow ascend isn't always an option. If this is the case, drink lots of water, take it easy and consider a medication...
Consider a medication
Talk to your doctor about a common prescription used to prevent altitude sickness called Acetazolamide or Diamox. You can live with the side-effects: it makes your hands and feet tingle, and carbonated drinks taste odd. Keep in mind, you'll need to take the medication before symptoms appear -- this is a preventative measure. There is also talk of using ibuprofin as a means to avoid the headache and nausea. But again, and as always, talk to your doctor about the best options available for you.
In many South American countries, drinking coca tea, or chewing coca leaves, is done by locals to combat altitude sickness. It is believed that doing such helps increase the absorption of oxygen in blood. I've heard mixed reviews, but if nothing else drinking the decaffeinated tea helps with hydration. Some people swear by it, others are indifferent. When I hiked the Inca Trail, I did not drink coca tea, and did not experience altitude sickness. Instead I drank a lot of water, allowed time to acclimatize and didn't overdue it. But I'm sort of inclined to recommend the "when in Rome" method...
While I'm on the subject of high elevations, now is a perfect time to remind you to wear your sunscreen. In high elevations you will find both less protective atmosphere in the form of a thinner ozone layer and high surface reflectivity in the form of snow and ice. So slather on that sunscreen!